Derivatives of Carboxylic Acids (A2)

A chemical compound derived from a carboxylic acid by replacing the -OH group with a -Cl group. For example, ethanoyl chloride is formed from ethanoic acid.

Acyl chlorides are formed by reacting a carboxylic acid with a reagent like phosphorus (V) chloride (PCl5), sulfur dichloride oxide (SOCl2), or phosphorus (III) chloride (PCl3).

Acyl chlorides are highly reactive due to the partial positive charge on the carbon atom of the carbonyl group, making it susceptible to attack by nucleophiles. This is because the chlorine and oxygen atoms pull electron density away from the carbon atom.

The process of breaking down an acyl chloride in the presence of water, resulting in the formation of a carboxylic acid and hydrochloric acid.

The relative ease of hydrolysis of acyl chlorides, alkyl chlorides, and aryl chlorides. Acyl chlorides hydrolyze most rapidly, followed by alkyl chlorides, and aryl chlorides are the least reactive.

Acyl chlorides are very reactive towards water, readily forming a carboxylic acid and hydrochloric acid, releasing heat and producing white fumes.

The hydrolysis of acyl chlorides can be further tested by reacting them with NaOH, followed by excess HNO3 and AgNO3. A white precipitate of AgCl indicates the presence of chloride ions.

The ease of hydrolysis of different chlorides is largely dependent on the reactivity of the carbon atom towards nucleophilic attack. Chlorine atom's electronegativity and electron-withdrawing effect make the carbon atom in acyl chlorides highly susceptible to nucleophilic attack, compared to alkyl and aryl chlorides.

Acyl chlorides react with alcohols at room temperature to form esters and HCl.

The reaction of an acyl chloride with a phenol is similar to the reaction with an alcohol, but requires warming.

Acyl chlorides react vigorously with ammonia to form amides and ammonium chloride.

The reaction with primary amines is similar to the reaction with ammonia, producing an amide and a salt.

Acyl chlorides react with water to form carboxylic acids and HCl.

The reaction of acyl chlorides with water, alcohols, and phenols is similar due to the hydroxide group (OH-) present in each molecule.

The reactions of acyl chlorides with ammonia and primary amines are similar because they both contain an amino group (NH2).

The reaction of acyl chlorides with alcohols, phenols, ammonia, and primary amines are all examples of nucleophilic acyl substitution reactions.

Electron-withdrawing groups make carboxylic acids more acidic by stabilizing the carboxylate ion, formed when the acid loses a proton. This stabilization happens because the electron-withdrawing group pulls electron density away from the negatively charged oxygen atom, making the ion more stable.

The strength of a carboxylic acid is determined by how easily it donates a proton (H+). The more readily it loses a proton, the stronger the acid. This ability is directly linked to the stability of the resulting carboxylate ion.

Carboxylic acids with more electronegative halogens (like fluorine) attached are more acidic. This is because the electronegative halogen pulls electron density away from the carboxyl group, making it easier for the proton to be released.

As the distance between the electron-withdrawing group and the carboxyl group increases, the acidity decreases. This is because the electron-withdrawing effect weakens with distance, making the carboxylate ion less stable.

Electron-withdrawing groups attached to aromatic rings increase the acidity of the aromatic acids. They work similarly to how they affect aliphatic carboxylic acids, by stabilizing the carboxylate ion and making it easier to lose a proton.

A reaction where a primary amine (concentrated) reacts with an acyl chloride at room temperature to form an N-substituted amide. This reaction is vigorous and produces a byproduct - ammonium chloride.

The ability of a carboxylic acid to donate a proton (H+) in solution. It forms a carboxylate ion and a hydronium ion. The strength of the acid is determined by the position of the equilibrium, with stronger acids having a greater tendency to donate protons.

Carboxylic acids are weak acids compared to strong acids like HCl or H2SO4, meaning they donate protons (H+) less readily.

A substituent group attached to a carbon chain that pushes electron density towards the carboxyl group. This reduces the ability of the carboxylic acid to donate a proton, making it a weaker acid.

A substituent group attached to a carbon chain that pulls electron density away from the carboxyl group. This increases the ability of the carboxylic acid to donate a proton, making it a stronger acid.

A direct relationship between the strength of a carboxylic acid and the effect of substituent groups attached to the carbon chain. Electron- withdrawing groups increase acidity, while electron-donating groups decrease acidity.

A measure of the acidity of a solution. The lower the pKa value, the stronger the acid.

The process in which electrons move from a donor atom to a acceptor atom within the carboxylate ion, leading to a more stable distribution of charge.

Acyl chlorides, such as ethanoyl chloride (CH3COCl), are highly reactive due to the partial positive charge on the carbon atom in the carbonyl group (C=O). This positive charge makes the carbon atom susceptible to attack by nucleophiles.

The carbon atom connected to chlorine in an alkyl chloride, like chloroethane (CH3CH2Cl), carries a smaller partial positive charge compared to the carbon in an acyl chloride. This is because the carbon in alkyl chlorides is only attached to one electronegative chlorine atom, while the carbon in acyl chlorides is bonded to both a chlorine and a highly electronegative oxygen atom.

The ability of the methyl group (CH3) in alkyl chlorides to donate electrons reduces the partial positive charge on the carbon atom connected to the chlorine. This makes the carbon atom less susceptible to nucleophilic attack.

Aryl chlorides, such as chlorobenzene (C6H5Cl), are less reactive towards nucleophilic attack than acyl chlorides or alkyl chlorides. The delocalized π electron cloud in the benzene ring helps to compensate for the partial positive charge on the carbon atom connected to chlorine, making it less vulnerable to nucleophilic attack.

In reactions involving acyl chlorides, the attack of a nucleophile is facilitated by the shift of π electrons in the C=O bond. This allows the carbon atom to bond with the nucleophile before the chlorine atom is released, leading to the formation of an intermediate.

The attack of a nucleophile on an acyl chloride is influenced by the partial positive charge on the carbon atom of the carbonyl group. This positive charge makes the carbon atom susceptible to attack by nucleophiles, which are electron-rich species seeking a positive center to attack.

Hydrolysis of alkyl chlorides, which is the reaction with water, is a slow process unless specific conditions are provided, such as the addition of a base like NaOH and heat. This is because alkyl chlorides have a weaker partial positive charge on the carbon atom compared to acyl chlorides.

Acyl chlorides react readily with nucleophiles, including alcohols, phenols, and ammonia, due to the strong partial positive charge on the carbon atom in the carbonyl group. These reactions often lead to the formation of esters, amides, and other products.